RE: Wren Idle Problem (Again)
 

The ecu on my supersport has been doing odd things again with the idle this weekend. PW at idle is usually around 99. On startup many times but not always it goes up to 104 or 105, which is about 55,000 rpm, stabilises there, and then pushes the pw and the revs higher, up to 106 or 107 / 56,000 rpm, stays there for a while and then very very slowly brings it back down to 99/45,000rpm. Then at the end of the flight all the way down final approach and taxiing back in the engine is idling far too fast, I attach the data terminal and it is reading 105/55,000 rpm. On some other flights the idle is correct at the start and correct at landing. I tried the 5 seconds throttle up and 5 seconds throttle down but that did not solve it.

Why, once it has started and is idling too high already, does the ecu wait a while and then push the revs even higher?

Harry

RE: Wren Idle Problem (Again)
 

HarryC What is your stability delay set at? George

RE: Wren Idle Problem (Again)
 

050

"Why, once it has started and is idling too high already, does the ecu wait a while and then push the revs even higher?"
Gaspar, any response?

RE: Wren Idle Problem (Again)
 

While it may not be a problem to your installation, I did receive a 44 in for some minor repairs this week, and one of the issues was an unstable idle....upon first inspection, I did discover a plastic tie wrap that was used to hold all wiring, fuel & gas lines together upon exiting of the FOD. The fuel line was pinched almost entirely flat...I suspect the pump would surge, the fuel line would expand, motor would surge, pump would slow...and the process would start all over again. I'll post my findings in the next day or so.

RE: Wren Idle Problem (Again)
 

Gaspar?

RE: Wren Idle Problem (Again)
 

Only two posibilities.

1) If the power of the pump (Pw=xx) don't change while the engine accelerates, then clearly a pump/plumbing problem.
2) If it raise, the its the TX that is asking for more RPM. Had exactly the same issue yesterday with a M90 and a MPX4000 TX. Engine had unstable idle. One click less of trim and steady idle. Relearned the TX and all OK again.

Gaspar

RE: Wren Idle Problem (Again)
 

Sorry Gaspar but I don't accept that is an issue with this particular engine. Using the same Tx, same model memory without altering the Tx settings, the PST engine that was in this model before I changed it for the Supersport was rock steady at idle. The ECU brought the Supersport to start at an idle that was much too high, then increased the pw value then decreased it slowly all the way down to the correct idle.

Harry